1. Field of the Invention
The present invention relates to a display apparatus for use with a computer system, and, more particularly, to a process and computer monitor for supplying a power supply voltage from an internal power supply therein to computer peripherals via universal serial bus hubs.
2. Background Art
A typical personal computer may have an associated monitor serving as a display apparatus, a keyboard and a printer, a light pen or a plotter. The monitor associated with the computer is connected with a body of the computer via a video cable, such as a D-Sub cable or a BNC video cable. The computer provides video signals, e.g., red, green and blue video signals, vertical and horizontal synchronization signals, and overall information required to control the monitor, to the monitor through the video cable. Also, information indicative of the monitor-processed results from the monitor is provided to the computer through the video cable.
In addition to the keyboard and the monitor, if the other peripheral devices, such as a printer, a light pen, a plotter and the like, are connected with the conventional computer, the sheer number of cables begins to make the connections between the computer and the peripheral devices complicated. Also, since conventional computers are not always provided with a plug and play function, it is difficult for a user to connect the peripheral devices with the computer. A universal serial bus system has been developed in one effort to ameliorate some of these difficulties.
A monitor has five main sections, a power supply, a video signal processor, a horizontal and vertical synchronization signal processor, a monitor controller and a cathode ray tube. The power supply receives an alternating current voltage which is externally applied through a plug, and provides several levels of direct current voltages to respective monitor circuit components. Also, the power supply has a monitor power management system for reducing power consumption.
The monitor controller receives monitor driving information through the video cable connected with the computer and generates two groups of control signals, namely a first group of control signals Cv1-Cvn necessary for processing the red, green and blue video signals and a second group of control signals Cs1-Csm used to control screen and focus, in response to the monitor driving information.
The video signal processor is provided to process the video signals from the computer via the video cable in response to the first group of control signals Cv1-Cvn. The video signals processed thus are applied to electron guns of the cathode ray tube so that the electron guns can radiate beams corresponding to the red, green and blue video signals. The horizontal and vertical synchronization signal processor is provided to process horizontal and vertical synchronization signals hereinafter, referred to as "Hsync and Vsync") which are applied from the computer via the video cable and deflect the beams from the electron guns in a direction, so that screen and focus can be controlled. Other contemporary designs equip the monitor with an audio unit generating an audio signal and a voice input unit for converting an audio signal into an electrical signal. I have found that there is some difficulty in using the peripheral expansion function of the computer for these features of the monitor. I have also found that, since conventional monitors are not equipped with connectors for communicating with peripheral devices, plug and play functions can not be performed.
Further, contemporary designs fail to provide an adequate serial bus system required for effective peripheral expansion with these computers with such monitors. Among designs representative of contemporary practice in the art, Oprescu et al., U.S. Pat. No. 5,485,458, Bus Interconnect Circuit Including Port Control Logic For A Multiple Node Communication Network, issued on Jan. 16, 1996 discusses a dominant logic physical bus that is coupled to all ports in a node. This is part of a bus interconnect device including port control logic for a communication network having a plurality of multi-port nodes that are connected with point-to-point links. Van Steenbrugge U.S. Pat. No. 5,448,554, Data Communication System Based On A Serial Bus And A Monitor Station For Use With Such System, issued on Sep. 5, 1995, discusses a data communication system based on a serial bus and a monitor station for use with such system. The monitor station, irrespective of the source of a particular bit, allows for sampling such bit in that it emulates an uncommitted slave station. Floyd et al., U.S. Pat. No. 4,528,662, for a Multiplex Control System Having Enhanced Integrity, issued on Jul. 9, 1985 discusses a serial data communication system in which bidirectional serial data communication is effected between a central control station and one or more remote stations. Einolf, Jr. et al., U.S. Pat. No. 4,395,710, for a Bus Access Circuit For High Speed Digital Data Communication, issued on Jul. 26, 1983, discusses a serial data communications network in which a plurality of stations communicate among one another on a single serial bus. Means et al., U.S. Pat. No. 4,373,183, for a Bus Interface Units Sharing A Common Bus Using Distributed Control For Allocated Of the Bus, issued on Feb. 8, 1983, discusses a plurality of bus interface units (BIU) that are interconnected by the distributed system data bus and a serial bus allocation line. Each bus interface unit may in turn be connected to either one or several data processing units, an I/O port, or a bridge connecting to still another similar bus network. From my study of the contemporary practice and art, I find that there is a need for an effective peripheral expansion that permits effective use of the monitor of a computer, however, there is not yet even a serial bus that can produce such desired result.